Slotted brake disc's

[robbo]

I want to fit slotted brake disc's to my SF I know that I could use the disc's from later XS11's or XJ11 but they are like chickens teeth here in the UK and high shipping prices make it unrealistic to buy them from the US. Does anyone know if there are any other Yamaha models from that period that share the same disc's ? I know if you just go by part numbers there are no others, but I find it hard to believe no other bikes used the same disc's I did see on one site that the 650 maxim shared the same front disc's as the 1100 but you can't believe all thats on the web

[TADracer]

I cannot answer your question directly but if finding what you want fails, you can try cross drilling your discs. Several guys have done this as well as I. It can give you a very nice look and does help braking a bit.

All you need is a few VERY GOOD drills, a drill press and a pattern. And don't forget there will be a right and left hand pattern for the front discs.

[jetmechmarty]

To the best of my knowledge, those slotted rotors are XS11 only. The XS850 Special had them, but those rotors are smaller diameter than the XS1100 rotors.

[TopCatGr58]

Here's the tech tip on HOW to drill your own rotors!

http://www.xs11.com/forum/showthread.php?t=587

T.C.

[robbo]

Cheers for the replies guys. I have thought about drilling my rotors, I dont have a press drill, so I'll have to find out how much it will cost to have them drilled. Thanks for the templates TC they'll be a great help. I still have a gut feeling that some other bike would have rotors of the same diameter, thickness, offset etc. The early XJ750 Seca had the swirly wheels and slotted rotors so may try and get some info on those.

[Schming]

Cheers for the replies guys. I have thought about drilling my rotors, I dont have a press drill, so I'll have to find out how much it will cost to have them drilled. Thanks for the templates TC they'll be a great help. I still have a gut feeling that some other bike would have rotors of the same diameter, thickness, offset etc. The early XJ750 Seca had the swirly wheels and slotted rotors so may try and get some info on those.

The XJ 750 disc rotors are the same bolt pattern but are thinner than the Elevens.

Here's a pic of my drilled discs using the templates in the link provided by T.C. only I doubled the pattern on each disc:





Once set up, it only took me an hour and a half to drill each disc. I step drilled using HSS bits with cutting oil finishing with a "slight" 60 degree counter-sink.

[robbo]

Result

I spoke to a cousin of my partners who has a small engineering business, he told me I am welcome to go there and use his drill. I've printed off the templates, so thanks once again TC
Those rotors look good Schming

[jetmechmarty]

I still have a gut feeling that some other bike would have rotors of the same diameter, thickness, offset etc.

You are right. The XS650 shares front rotors with the XS1100. It just doesn't have the slots you're looking for.

[Ken Talbot]

The '81 XJ650 that SWMBO used to ride had the same slotted rotors as the XS11.

[CaptonZap]

I spoke to a cousin of my partners who has a small engineering business, he told me I am welcome to go there and use his drill. I've printed off the templates, so thanks once again TC
Those rotors look good Schming

If your partners cousin doesn't tell you, slow spindle speed, cutting oil, and unremitting pressure is the key to not burning up the drill bits. If you don't see a chip being cut, more pressure, or get a new sharp bit. Ease up when the bit starts through the back side, so as not to jam the bit. You can feel it, and usually hear it as it starts to break through.
A split point drill, 1/8 inch in diameter is a good start, then increase the size to about half of the finish diameter, then go full size.

CZ

[bikerphil]

Just to add, do not let the rotor get too hot when drilling, there is a good chance of it warping out of spec, DAMHIK.

[jetmechmarty]

The '81 XJ650 that SWMBO used to ride had the same slotted rotors as the XS11.

The parts fiche doesn't show the XJ650 rotor being slotted. Are you sure that's not an XS1100 rotor?

[MaximPhil]

Hi Marty,
My XJ650 has a solid front rotor. I think it is thinner than the XS rotor or is that just wear
Phil

[Ken Talbot]

The parts fiche doesn't show the XJ650 rotor being slotted. Are you sure that's not an XS1100 rotor?

Hmmm... Could be that the rotor had been swapped out before we got it! It was there when we bought it, just assumed it must have been original...

[Ken Talbot]

A split point drill, 1/8 inch in diameter is a good start, then increase the size to about half of the finish diameter, then go full size.

CZ

FWIW - when I drilled mine, I drilled them to "final size" in a single pass. Like CaptonZap says, use lots of fluid, and alter your feed pressure as required to maintain a nice consistent curl.